Immunohistochemistry Expression of VEGF and CD34 was analyzed in 75 (50 placenta of IUGR and 25 of control) placental villous tissues. Samples (1.5 × 1.5 × 1 cm in diameter) taken from the maternal surface of each placenta; infarct areas were excluded from the study. All tissues were fixed in formalin, embedded in paraffin, and cut into 5-μm-thick sections, which were collected on slides coated with poly-L-lysine. After the paraffin was removed, the sections were rehydrated.